Thunderstorms, Tornadoes, And Hurricanes

( Originally Published Early 1900's )

IN ancient days before men understood the scientific reasons for severe storms, and when people were superstitious, thunder-storms, tornadoes, or other types of storms were thought by many to be produced by the gods, who had be-come angry because of the people's misdeeds. The long rolling peals of thunder shaking the very earth were explained as the expression of their wrath, while the flashes of brilliant blue zig-zag lightning shooting forth from the heavens seemed to be intended to strike down the wicked, or to terrify those who had not behaved properly. Fortunately, no longer do we believe as our ancestors of old. Thunder-storms may not only be accounted for, but they can be forecast. How-ever, some persons still fear thunderstorms when they really should not, for their dangers are few.

If we could actually look into people's brains to learn what their thoughts are when they show fright during a storm, we would probably discover that the crashes of thunder rather than the lightning produced fear. Likewise, when the squally wind howls through the door-jambs and window-casings, people fear the noise of the wind more than the rain or pelting hail which it carries. As a matter of fact, thunder-storms are much less dangerous to life than our automobiles, yet most of us do not fear automobile rides.

Thunder, of course, does no damage, as it is merely the noise resulting from the atomic disturbance of the air through which the lightning discharge takes place. It is similar to the click which we sometimes hear when on a cold dry night we run a comb through our hair. This click or sign of a discharge of electricity differs from thunder only in the amount of noise. If people are going to be afraid of storms, they should fear the lightning and not the thunder.

Lightning is not very dangerous if we observe a few simple rules. Never stand under a tree during a storm, because trees are excellent conductors of electricity and they are frequently struck by lightning. Trees are tall and pointed and, besides, their roots go deep into the moist earth, thus forming an easy path along which lightning may travel. If a tree is struck, people or live stock seeking shelter under it almost certainly will be shocked and in most instances killed. Trees mark danger spots during thunder-storms. They should be avoided.

We are much safer indoors than out-of-doors during thunder-storms, but even in our homes certain precautions are advisable. Since lightning generally strikes high points, there always is the possibility of its hitting a chimney. If the chimney contains warm air, the lightning may follow the air down to the fireplace opening into our room. While this may happen only once in a great while, and in most homes never occurs, yet it is well to play safe and no-t sit close to the fireplace or between it and an open door. In fact, we should keep all of our doors and windows closed during a storm, so as to prevent the formation of warm air drafts. Warm air is a much better conductor of lightning than cold air.

In our large cities lightning :rarely strikes a house because there are so many electric wires all around. The street-railway trolley wires, the telegraph, telephone, and electric-light wires, all conduct electricity. They are so much better conductors than wood and brick buildings that if lightning tends toward these structures, the wires near-by carry off the charge. On the other hand, in the rural districts where buildings are located in the center of large flat areas, all of them should have lightning-rods attached. Oftentimes farm houses, barns, silos, and other structures are the only high points in the region, and therefore lightning discharging toward the earth near them is likely to strike them. Experience of fire-insurance companies has shown that most buildings in small towns and rural districts which have lightning-rods properly attached., with the lower end reaching well down into the moist soil, are in no danger of damage from lightning. The rod may be struck, but it carries off the electricity into the earth and saves the building from injury. Steel sky-scrapers are safe because, when lightning strikes them, all of the girders act just like lightning-rods and carry off the lightning.

Many persons say lightning never strikes in the same place twice. This is not true. Those who have studied lightning records and the behavior of lightning itself tell of many instances in which lightning has struck in the same place several times. If lightning has struck a certain place once, do not seek it out for shelter in another storm, thinking it won't be struck again.

Perhaps the greatest damage done by lightning occurs in the forested areas, particularly in the western part of the United States, where it is one of the most common causes of fire. The tall spires of our evergreen trees, especially pines and spruces, invite lightning discharges, and the resin in these trees furnishes excellent tinder for fires. Oak-trees are said to attract lightning more readily than any other types, but they do not catch fire so easily. It is estimated that lightning starts more than 3,000 forest fires in the United States every year. Although lightning is dangerous, yet when one considers the millions and millions of flashes every year and the few persons who are struck by them, we may really look upon lightning as among the least dangerous of the hazards which man must meet.

You have often heard your friends remark about their having been caught suddenly in a thunder-storm. They may say that a thunder-storm "came up before they knew it." The storm probably did take them by surprise, not because it developed suddenly, but because they them-selves knew nothing about thunder-storm formation and consequently did not observe the advance warnings of the storm. Just learning a few simple facts relative to these storms will oftentimes save us inconvenience.

In our discussion of clouds you will recall we described the impressive thunder-head or cumulo-nimbus cloud with its dark straight-line base from which rise massive white-domed projections. If you watch this cloud for a while you will see its outline constantly changing, except the straight horizontal base. You will remember too that this cloud is of the convection type that is, its form depends upon currents of warm air rising from the earth accompanied by a considerable amount of water vapor. In other words, the two elements necessary to bring about this cloud formation are a high temperature and a high relative humidity at the earth's surface. On days that are "sticky," especially before noon and when the temperature hovers around the 75° F. mark or above, we may begin to scan the sky for thunder-heads, and if they show upon the horizon while the humidity continues high, the prospects for a thunder-storm by mid-afternoon are very good. If you should happen to own a barometer and you notice at this time that it reads not only low, but shows no inclination to rise, then you can be almost certain that a thunder-storm will break before the day ends. Since thunder-storms nearly always come from the southwest, west, or northwest in the United States, the first place to look for them is along the western horizon. They do not happen so suddenly that we cannot become aware of their approach at least five or six hours before their arrival. Thunder-storms surprise only those people who ignore the skies.

Because of the havoc which thunder-storms sometimes create, we might have the impression that they possess no value. But nothing could be farther from the truth. They are worth many mil-lions of dollars each year. For example, our largest cereal crop, corn, of which we produce on the average 3,000,000,000 bushels annually, thrives best in a climate which has hot summers, especially hot nights, a fair amount of rainfall, and where sunshine is abundant. The ordinary type of rainfall in the form of an all-day shower will not do for corn. It must have both rain and sun-shine, a combination provided only by the thunder-storm type of summer climate. Showers from these storms are fairly heavy when they occur, assuring abundant moisture, last just a little while, from a few minutes to three or four hours, and then are followed by sunshine. The corn belt has been called the thunder-shower belt. This is a good name, because in the corn belt, thunder-showers occur more frequently than in most other regions north or south of the equatorial districts. Many other crops are likewise benefited by thunder-storms. At the end of weeks of summer drought, thunder-showers usually afford the first break and relieve the danger of general crop failures.

Even man derives direct good from thunderstorms. Those of us who live in the Mississippi Valley wish on many a hot sultry summer's day for a thunder-storm to bring showers, to lay the dust, clear the air, and to lower the temperature sufficiently to afford relief for the evening and enable us to secure a much-needed comfortable night's rest in preparation, perhaps, for another trying hot day.

A close relative of the thunder-storm, if not of the same family, is the dreaded tornado. Should any one ever see a tornado coming toward him, he not only has a right to fear it, but he should fear it, for it is the most destructive of all storms. Once caught within a tornado, the chances of escaping with one's life or without serious injury are almost nil. Happily, however, unlike thunder-storms, tornadoes do not occur frequently. Even in those parts of the United States known as "tornado zones," people do not live in fear of these storms. Many of them have "cyclone cellars" that is, types of dugouts or root cellars below ground into which they can run for protection should they suddenly find themselves in the path of a tornado. The regions most susceptible to tornadoes may be described as a belt from Texas to Ohio, although any part of the plains or low rolling hill areas east of the Rocky Mountains may be visited by these night-mares from the clouds.

When tornadoes develop they usually accompany thunder-storms, but differ from them in always including a funnel-shaped whirling cloud. This frightening spiral moves across country at a rate of thirty to fifty miles an hour. Its green-gray to yellowish-black terrifying color, its tremendous internal velocity, its roaring and crashing noises frighten the bravest of men. The heavens are described by those who have seen these storms as ghastly, and just before the tornado strikes, the cloud-covering as a whole is so dense that daylight is turned into darkness. Within the tornado itself the wind velocity is higher than that of any other wind. More than 100 miles an hour is certain, while estimates place the velocity at from 300 to 500 miles an hour. We have no accurate records, because when such a storm passes over a Weather Bureau station the instrument for recording wind velocity is destroyed before it can show the maximum velocity.

The damage to property runs into millions of dollars and the loss of life may be high when tornadoes strike densely populated localities. Recent figures show that as many as 140 tornadoes have been reported in the United States by our Weather Bureau in a single year; in one year as many as 794 persons have been killed and property damage has reached as high as $47,000,000.

The nature of the damage done by these storms is most interesting. The cloud itself being very definite and the wind velocity of tremendous power, the destruction it often wreaks reminds one of what might have been caused by a large knife whose cutting edge is so sharp nothing can resist it. Buildings are cut in two, one half being carried away and the other left standing as though no storm had touched it. A tree might be cut through the center, the top portion re-moved and a stump left, or the whole thing might be uprooted and carried away, leaving a hole in the ground as clean and neatly dug out as though man had done it carefully. If you were told that a weak straw such as you might take from a bale of hay can be driven several inches into a tree trunk, or straight through a two-inch scant-ling, you might hesitate to believe the tale. Yet tornadoes have accomplished this "trick" hundreds of times.

Although we have said that tornadoes may justifiably be feared, yet some odd antics of these storms indicate that it is possible to be caught in them and still be fortunate enough to escape without even a scratch. A family has been at dinner when a tornado suddenly enveloping the house has carried off the roof, blown out the windows and walls, and left every one still sitting at the table unharmed. "How can this be possible ?" one may ask. Within the tornado cloud the wind is moving so fast, and in an upward spiral direction, that the condition produced there is similar to a vacuum. When this near-vacuum incloses the house, the normal pressure of the air indoors has no time to change. Under these circumstances a higher pressure exists in-doors than out-of-doors, and as a result the roof and walls are forced out. In fact, as one of the evidences of a tornado, we look for this sort of action. Many persons experiencing a very severe thunder-storm accompanied by high damaging winds may claim to have experienced a tornado, but if they will tell you that windows were blown in and not out, doors forced in and not out, garage walls blown down toward each other, then you may be sure they were not in a tornado but merely in a thunder-squall.

Those persons who have seen tornadoes may know how to protect themselves the next time they experience one, but millions of people have never seen such storms nor even been near them. For these persons a practical suggestion may be worth while, provided they can keep their wits about them when they see the tornado coming.

Tornadoes generally travel in well-defined paths from southwest to northeast and cover an area usually not more than about a quarter of a mile wide. The path may be much narrower than this. If a tornado approaches from the southwest and we are not near a "cyclone cellar" but there is still time to run, we should run toward the north or northwest. Never run in other directions, because you may plunge right into the center of the storm's path or be overtaken by the storm. Tornadoes are so definite in out-line that a person might be standing on one side of a street without feeling even so much as a strong wind, while buildings on the opposite side may be demolished even to the point of their complete disappearance. If we have no time to run from the storm or to get into a "cyclone cellar," and we are indoors, we should seek safety in the southwest corner of the basement; or if we happen to be out-of-doors, we should lie flat on the ground, preferably in a depression, face downward and arms stretched out full length ahead.

We have referred several times to "cyclone cellars." These should be called tornado cellars, because, as we shall show later, cyclones and tornadoes are not the same thing. Cyclones pass over us every three or four days, are quite harmless, and very different from the terrible tornado. However, the word "cyclone" has been used so long by so many people when they mean "tornado" that it is difficult now to establish correct usage for the term.

Tornadoes sometimes cross lakes or ponds. Then the funnel-shaped cloud with its vacuum invites the water to rush up into it. The difference in pressure outside the tornado and inside forces the water to rise. The column of water may not rise very high, perhaps not over ten or fifteen feet. When the tornado reaches the shore again it may continue over the land, resuming its characteristic land aspects. It is interesting to note that when a spout passes out to sea, only the water in the lower portion is salt. That in the upper part is fresh, because it has come from the condensed water vapor of the atmosphere.

Hurricanes rank only second to tornadoes in violence. They are not accompanied by the funnel-shaped cloud, but their wind velocity often reaches 150 miles an hour and the width of their path exceeds that of the tornado by miles. Since their path is so wide they may travel hundreds of miles while tornadoes usually travel less than one hundred miles, and frequently only five or ten miles, or even as short a distance as a few thousand feet, the total destruction wrought by a hurricane may greatly exceed that by a tornado.

The most famous hurricanes are known as the West Indian. They originate, so far as we know, off the west coast of Africa in the warm calms over the Atlantic Ocean and travel west-ward toward the West Indies. Porto Rico is commonly visited by them. They often continue from Porto Rico toward the west or northwest until the Florida coast of the Gulf of Mexico is reached, where the storms recurve toward the northeast and travel with diminished force along the south Atlantic coast about as far as Cape Hatteras. Here they pass out to the Atlantic Ocean, where the air over the cool northerly waters reduces their energy to that of just ordinary storms.

Instead of turning at the Florida coast, hurricanes may travel across the Gulf of Mexico, as did the remarkable hurricane of the year 1900, which demolished Galveston, killing thousands of people. This storm, which is now always referred to as the Galveston Hurricane, after leaving Galveston, turned northeastward up the Mississippi Valley to the Great Lakes region and then down the St. Lawrence, causing great damage everywhere. Of course, as it went farther inland its strength decreased, but nevertheless it proved severe nearly everywhere.

Hurricanes are the only type of storm in the northern hemisphere which travel considerable distances from east to west. All other storms travel in a general west to east direction from the time of their origin until they break up.

In recent years these hurricanes have caused consternation in Florida because of the increased settlement of that State. The number of hurricanes has shown no particular increase, but our attention has been directed to them more often than in the past because, with a denser population and more buildings in Florida, the damage has impressed the world more than when the region was unoccupied. It is with storms much as it is with earthquakes. The latter occur somewhere on the earth every day, but we don't hear much or anything about them unless they happen where people's homes and places of business are. Then the destruction caused by the earthquake becomes exciting news for everybody. When storms kill people and destroy buildings the public becomes intensely interested.

The West Indiai hurricanes may occur in any month of the year, but they are most frequent during late August, September, October, and early November. These are known as the hurricane months, and any one visiting the region of these storms at that time of the year must expect the possibility of experiencing a hurricane. The winds in these storms are of tremendous velocity, and the rainfall is torrential. Lowlands are flooded and the levels of small lakes and ponds are raised at times several feet, enough to flood the land for some distance all around them. Then, too, as the hurricane approaches the coast, the waters of the sea which have been piled up move toward the land in a kind of tidal wave. If there are settlements along these shores, they may be flooded out. In order to prevent future disasters of this sort sea-walls are being built. At Galveston a wall was constructed along the top of which is an automobile drive. The people hope it will be strong enough to stop hurricane waves should they ever happen again along their shore.